import java.io.*;
import java.util.*;

class N570 {
	public static void main(String[] args) throws Exception{
		try (Scanner sc1 = new Scanner(System.in)) {
			int[] array = new int[3];
			String[] label = new String[]{"A", "B", "C"};
			array[0] = Integer.parseInt(sc1.next());
			array[1] = Integer.parseInt(sc1.next());
			array[2] = Integer.parseInt(sc1.next());

			for(int i = 0; i < array.length; i++){
				for(int j = 0; j < array.length - 1 - i; j++){
					if(array[j] > array[j + 1]){
						int tmp = array[j];
						String tmp2 = label[j];
						
						array[j] = array[j + 1];
						label[j] = label[j + 1];
						
						array[j + 1] = tmp;
						label[j + 1] = tmp2;
						
					}
				}
			}
			
			for(int k = label.length; k > 0; k--){
				System.out.println(label[k - 1]);
			}
		}
	}
}